Device for cutting an outer layer of the concentric multilayer rod-like structure

ABSTRACT

Apparatus for stripping a selected length of sheathing from a coaxial cable and the like. A die is positioned about the coaxial cable and a hollow cylindrical-shaped die is inserted beneath the sheathing to a depth commensurate with the amount to be stripped, accurate adjustment being controlled by an interior mounted slidable scale member. The two die members are brought into abrupt engagement with one another by being moved either linearly and/or rotationally relative to one another whereby the selected length of sheathing is stripped therefrom.

United States Patent Kamimura et al.

]March 20, 1973 DEVICE FOR CUTTING AN OUTER LAYER OF THE CONCENTRICMULTILAYER ROD-LIKE STRUCTURE Inventors: Masato Kamimura; Saburo Fukui,

both of Tokyo, Japan Assignee: Nippon Electric Company, Limited,

Tokyo, Japan Filed: Sept. 3, 1970 Appl. No: 69,287

Foreign Application Priority Data Sept. 4, 1969 Japan ..44/70444 US. Cl..8I/9.5l Int. Cl. ..I-I02g l/l2 Field of Search ..8 l/9.5 l, 9.5 R, 9.5A

References Cited UNITED STATES PATENTS Barrans et al .8l/9.5l UX3,153,358 10/1964 Havens ..8l/9.5l 3,171,306 3/1965 Mirsch ,.8l/9.5l

FOREIGN PATENTS OR APPLICATIONS 126,534 5/1959 U.S.S.R SI/9.51

Primary Examiner-Robert C. Riordon Assistant ExaminerRoscoe V. Parker,Jr. Attorney0strolenk, Faber, Gerb & Soffen [5 7 ABSTRACT Apparatus forstripping a selected length of sheathing from a coaxial cable and thelike. A die is positioned about the coaxial cable and a hollowcylindricalshaped die is inserted beneath the sheathing to a depthcommensurate with the amount to be stripped, accurate adjustment beingcontrolled by an interior mounted slidable scale member. The two diemembers are brought into abrupt engagement with one another by beingmoved either linearly and/or rotationally relative to one anotherwhereby the selected length of sheathing is stripped therefrom.

2 Claims, 7 Drawing Figures DEVICE FOR CUTTING AN OUTER LAYER OF THECONCENTRIC MULTILAYER ROD-LIKE STRUCTURE The present invention relatesto cable and the like and more particularly to cable of the coaxial typeincluding a sheath or layer of shielding cable and apparatus forremoving selected end portions therefrom.

Cables of the type typically employed in the electrical and electronicfields normally have its sheathing stripped by selected amounts toprovide for electrical connection between a conductor and associatedelectrical or electronic circuitry. One type of cable, typicallyreferred to as coaxial cable, is comprisedof a conductive cordsurrounded by an insulating sleeve which, in turn, is surrounded by ametallic sheathing which ultimately is contained within an outermostinsulating layer. In order that connection be made to electricalcircuitry, it is typical to strip away the outermost insulating layer toa maximum amount and to strip away the conductive shielding and innerinsulating layer to graduated lesser amounts so as to expose theconductive sheathing and conductive cord by predetermined amounts andthereby enable a rather simple, straightforward electrical connectionthereto. Initially the outermost insulating layer is first stripped awayexposing the conductive sheathing or knitted layer, a portion of whichmust also be stripped away. The stripping operation is typicallyperformed manually with a pair of scissors or tool, such as, forexample, a stripper. It has been experienced that such tools have shownthat the stripping operation is highly inefficient from the viewpoint ofperformance and that the result of the stripping operation manifestsitself in an uneven and in fact an unsatisfactory condition. In additionthereto, cutting of the conductive sheathing is made more difficult whenthe thickness thereof is rather substantial.

The present invention is characterized by providing an apparatus forstripping conductive sheathing in a neat, effective and simple mannerregardless of sheath thickness.

The present invention is comprised of a punch and corresponding diemember which are arranged to engage the outer and inner faces,respectively, of a conductive sheathing layer and to efficiently cut thedesired length therefrom through their cooperative action which may berelative linear and/or rotational movement. Adjustable means areprovided for automatically regulating the amount of sheathing to be cutaway through positioning of the inner conductive core and innerinsulating layer in abutting relationship with the adjustable means tothereby further simplify perform ance of the operation.

It is therefore one primary object of the present invention to provide asimplified reliable apparatus for cutting a selected length of sheathingfrom a coaxial cablc.

Another object of the present invention is to provide a simplifiedreliable apparatus for cutting a selected length of sheathing from acoaxial cable and whereby further adjustable means are provided fordefining insertion depths of the punch into the cord therebyautomatically regulating the length of cord to be removed.

Another object of the present invention is to provide a novel apparatusfor removing selected lengths of sheathing from coaxial cable and thelike through the cooperative use ofa die and punch in which at least oneof said members has a tapered cutting edge to facilitate the cuttingoperation.

Still another object of the present invention is to provide a simplifiedreliable apparatus for cutting a selected length of sheathing from acoaxial cable and whereby relative and linear and/or rotational movementbetween the cutting members is brought into play to effect the cuttingoperation.

These as well as other objects of the present invention will becomeapparent from a consideration of the following description and drawings,in which:

FIG. 1 is a perspective view showing the coaxial cable having a portionof its outer insulating sheath stripped away and in which the method andapparatus of the present invention may be used to great advantage forstripping away selected lengths of knitted conductive shield layers.

FIG. 2 is a perspective view showing a coaxial cable of the type shownin FIG. 1 after removal of a selected length of the knitted layer hasbeen effectuated through the method and apparatus of the presentinvention.

FIG. 3 shows a longitudinal sectional view of a major portion of theembodiment of the present invention incorporating its salientprinciples.

FIG. 4A-4C are longitudinal sectional views of the cutting device shownin FIG. 3 illustrating the chronological steps employed in performingthe cutting operation, wherein FIG. 4A shows the state in which thecoaxial cord is first inserted into the cutting device and just beforecutting thereof; FIG. 4B shows the state in which the knitted layer iscut; and FIG. 4C shows the state in which the cutaway portion of theknitted layer has been stripped off after the cutting operation.

FIG. 5 is a longitudinal sectional view showing a modified form of thecutting section of the present invention with certain elements beingbroken away to facilitate an explanation thereof.

FIGS. 1 and 2 show coaxial cable having an outer insulating sleeve orsheath 1 whose left-hand portion has been cut away so that theleft-handmost edge is at la. This cut away portion exposes a conductiveshield knitted layer 2 which lies between outer layer 1 and an innerinsulating layer 3 which surrounds a conductive core C. The strippingoperation sequence is comprised of the steps of first removing a portionof the outer insulating sleeve 1; removing a portion of the left-handend of the knitted sleeve 2 and ultimately removing a portion of theinner insulating sleeve 3 so as to expose a sufficient length of theconductive core C to permit electrical connection thereto. FIG. 2 showsthe knitted sleeve 2 having a left-hand end portion thereof removed sothat its left-handmost edge lies at 2a. Heretofore certain types ofscissors or tools such as strippers have been employed for cutting theknitted shield. It has been found that the use of scissors is aninefficient method in that it is difficult to use the scissors as wellas to produce a neat final appearance. Cutting also becomes extremelydifficult when the thickness of the knitted soft copper wire issubstantial. Certain stripper-like tools having plural cutting edgeswhose outer periphery corresponds to that of the shield knitted layer tobe cut, make a deep cut into the knitted layer after which the cut awayportion is removed by pulling the coaxial cord in the linear direction.The use of such stripping tools has been found to be unsatisfactory dueto the fact that the knitted shield itself is unevenly cut and furtherdue to the fact that the stripper like tool gouges into the insulationlayer 3, yielding an unsatisfactory end product. FIG. 3 shows the mostimportant components of the cutting device and method of the presentinvention which is comprised of a hollow main shaft 4 supported by amachine frame F so as to be freely movable in the axial direction. Apunch 5 provided with a wide diameter opening 50 which steps abruptlyinto a narrow diameter opening 5a, has its wider diameter openingdetachably mounted to the left-hand end of shaft 4 in the manner shown.The central openings 40 and 5a of members 4 and 5, respectively, are inalignment with one another so as to permit the passage therethrough ofascale shaft 6 which is freely slidable in the axial direction withincentral opening 4a. The diameter of opening 50 in punch 5 issubstantially equal to the outer diameter of the polyethyleneinstallation layer 3, as shown in FIG. 2, and has a relatively smallgauge shell thickness to facilitate insertion of the polyethylene layer3 into interior 50 while the knitted shield may be slipped over theexterior of punch 5. The dimensional relationships of the Figures havebeen chosen merely for purposes of facilitating a showing oftheapparatus.

The left-hand end of scale shaft 6 is provided with a probe 6a ofsubstantially reduce diameter and which extends into the shaft opening50 so as to function as a stop to limit the entry of the insulationportion 3 to a selected depth. The insulation 3 is urged into shaft hole5 to thereby define a predetermined length of the shield knitted layerwhich is desired to be removed. Graduations may be provided along thelength of scale shaft 6 to form a scale portion in the vicinity of itsright-hand end, as shown in FIG. 3, in order to accurately adjust theshaft scale to a desired setting determinative of the amount of knittedshield to be removed. The graduations of the scale portion 6b cooperatewith the righthand end of opening 4a in main shaft 4 to establish theappropriate reading. A set screw 7 threadedly engages a tapped opening4b in main shaft 4 and may be urged against the surface of scale shaft 6to rigidly maintain the scale shaft in a desired position and therebyprevent movement of the scale shaft relative to main shaft 4 when thecutting operation is in process.

Whereas the thickness of the probe portion 6a provided at the left-handend of scale shaft 6 is not critical it should be understood that asmall diameter probe is preferred so as to accommodate a wider range ofpunch members 5 whose inner diameters may be significantly smaller thanthat shown in FIG. 3, thereby enabling the apparatus of FIG. 3 to beemployed for use in stripping the knitted shield of coaxial cableshaving a wide range of diameters. Coaxial cable of different diametersmay he so stripped simply by removing the releasably mounted punch 5 andcooperating die 8 (to be more fully described) to accommodate the nextcoaxial cable to he so stripped.

Once the scale shaft 6 has been appropriately adjusted, the main shaft 4may be moved by any suitable means in a linear fashion (from right toleft) which movement (arrow l3-FIG. 4B) is directly imparted to thepunch 5 for a purpose to be more fully described.

Die 8 has its central axis coincident with the central axis of mainshaft 4 and punch 5 and is mounted within an opening provided in themachine frame F and likewise aligned with punch 5 as is shown. Die 8 isheld in position by means of a tapped binding nut 9 which threadedlyengages a threaded portion of die 8. The right-hand portion of the dieis provided with a flange 8d which bears against the right-hand surfaceof the machine frame F arid surrounding the opening in Frame F so as tobe rigidly held in position. Die 8 may be easily removed and replaced bya die of other dimensions to accommodate the stripping of coaxial cableof commensurate dimensions when desired.

Die 8 is provided with a central opening consisting of a constantdiameter portion 8a and a tapered diameter portion 8b of substantiallytruncated conical shape and integrally extending therefrom. The diameterof the opening portion 8a is dimensioned so as to receive the pointedend 5b of punch 5 with an appropriate clearance therebetween.

FIGS. 4A-4C show the chronological steps in the stripping operation.Making reference to FIG. 4A, the coaxial cable 10, after having had aportion of the outer insulating layer stripped therefrom (the right-handend thereof relative to FIGS. 4A-4C) is inserted through die 8 in thedirection shown by arrow 12 and is advanced still further so that theinsulating layer 3 enters into the opening 50 in punch 5 and the knittedshield layer 2 surrounds the outer surface of punch 5. Insertion iscompleted when the right-hand end of layer 3 abuts against the left-handend of probe 6a which has previously been set to establish the amount ofknitted shield layer 2 to be removed. Thus, a portion of the left-handend of punch 5 is embraced between insulating layer 3 which lies in itsinterior and knitted shield layer 2 which surrounds its exterior.

The main shaft 4 is then linearly moved in the direction shown by arrow13 in FIG. 48 until the pointed end of punch 5 reaches die 8 and beginsto advance into the constant diameter hole portion 8a, at which time theknitted shield layer 2 is cut by the cooperating action between punch 5and die 8 along the circumference perpendicular to the coaxial cablecentral axis, the cutting edges being the outer peripheral cutting edgeof the punchs pointed end and the inner peripheral cutting edge of thedie hole opening portion 8a.

FIG. 4C shows the state wherein the punch S has its left-hand endadvanced to a small degree into the opening in die 8, resulting in thecutting of a portion of the knitted shield layer 2a from the coaxialcable. After cutting, the coaxial cable is withdrawn by being moved inthe direction shown by arrow 14 whereby the eutaway knitted end portion2a remains on the outer periphery of the left-hand end of punch 5. Thecutting operation having been completed, the coaxial cable 10 may befully withdrawn from die 8 preparatory to the next operation which maytypically be removal of a portion of insulating layer 3 to expose ashort length of the conductive core (not shown).

In putting the present invention into practice, it is necessary to presspunch 5 against die 8 with the force sufficient to effect the cuttingoperation. In this connection any well know pressing means may be used.It should be obvious that, to obtain a cutting device having the desiredperformance, the necessary drive may be obtained through an electricmotor with appropriate mechanical linkages to main shaft 4 by compressedair or other power sources, as well as a system in which a rack R isintegrally joined to main shaft 4 and a meshing pinion gear G providedwith a manually operable handle H may be employed to rotate the piniongear and thereby linearly move main shaft 4 as a result of the meshingengagement therebetween.

Although the cutting operation was described in the foregoing embodimentas being effected through the movement of punch 5 while retaining die 8stationary, it should be obvious that the punch 5 and main shaft 4 maybe held stationary and die 8 may be moved toward punch 5 to perform thecutting operation with equal success. Alternatively, both punch S anddie 8 may be substantially simultaneously moved in reciprocating fashionto perform the cutting and removing operation.

The cutting device of the present invention is of the type in which thecutting of the knitted shield layer and the like is effected through theshearing action of punch 5 and die 8. To produce such an accurate andeffective shearing effect, a modification of the preferred embodiment,as is shown in FIG. 5 may be employed in which die 8 is provided with atapered mouth portion having a tapered face 12 which comes intoengagement with punch 11 which is provided with an edge of a pointedend. Alternatively, the punch may be provided with a tapered pointed endhaving a tapered face which comes into engagement with the die which isprovided with an edge of a mouth portion thereof.

Cutting efficiency may be further enhanced by providing relativerotational movement between punch 5 and die 8. For example, main shaft 4and punch 5 may be rotated while die 8 is held stationary, die 8 may berotated while punch 5 is held stationary, or both punch 5 and die 8 maybe simultaneously rotated in opposing directions.

As will be apparent from the foregoing description, the cutting deviceof the present invention is effective for use in cutting the shieldknitted layer of a coaxial cord. However, the present invention is alsowidely applicable to cables of the concentric multilayer type other thancoaxial cable and may be used to cut outer layers of any type orconstruction as the occasion demands, without departing from the spiritand scope of the present invention. Therefore, this invention is to belimited, not by the specific disclosure herein, but only by theappending claims.

We claim:

1. A cutting device for stripping a desired length of an outer flexiblesheath ofa concentric multi-layer rodlike structure such as a coaxialcable comprising:

a die having an opening ofa diameter which substantially corresponds tothe outer diameter of said sheath, one end of said opening being anentry end and the other end of said opening being a stripping end, saiddie opening being provided with a constant diameter portion contiguousto the end surface of said die surrounding the stripping end and beingadapted to receive the free end portion of the multi-layer cableinserted into said entry end whereby a portion of the multilayer cableaxially slidably projects beyond the end surface adjacent said strippingend;

a thin hollow cylindrical straight punch member having an inner diametercorresponding substantially to the inner diameter of said sheath andhaving an outer diameter fitting said constant diameter portion of saiddie with a predetermined clearance, said punch member being adapted tobe inserted inside said sheath whereby a substantial portion of saiddesired length of said sheath is supported by said punch member, theshell thickness of said punch member being constant and being of a smallgauge to facilitate slipping of the sheath over the outer surface of thepunch member; and

means for holding said punch member and said die in concentricallyaligned relationship and allowing relative linear movement between saidpunch and said die;

said relative movement bringing a cutting edge provided by the outerperipheral edge of the free end of said punch member into proximity ofanother cutting edge provided between said constant diameter portion andthe surface of said die adjacent the stripping end of the opening insaid die with said sheath interposed therebetween and then the endportion of said punch member within said constant diameter portionwhereby said sheath is sheared along a line defined by said cuttingedges of said die and punch brought into proximity.

2. The device of claim 1 further comprising: a shaft axially slidablyinserted within the opening in said punch and having a first end forabutting the free end of a cable inserted into said punch member; and

means coupled to the opposite end of said shaft for adjustablypositioning said shaft within said punch member;

said punch member being adjusted to be positioned beneath the exposedconcentric layer to be removed wherein the underlying concentric layerextends into the opening of said punch and abuts the end of saidadjustable shaft to thereby control the length of the exposed concentriclayer positioned about said punch member.

1. A cutting device for stripping a desired length of an outer flexiblesheath of a concentric multi-layer rod-like structure such as a coaxialcable comprising: a die having an opening of a diameter whichsubstantially corresponds to the outer diameter of said sheath, one endof said opening being an entry end and the other end of said openingbeing a stripping end, said die opening being provided with a constantdiameter portion contiguous to the end surface of said die surroundingthe stripping end and being adapted to receive the free end portion ofthe multi-layer cable inserted into said entry end whereby a portion ofthe multilayer cable axially slidably projects beyond the end surfaceadjacent said stripping end; a thin hollow cylindrical straight punchmember having an inner diameter corresponding substantially to the innerdiameter of said sheath and having an outer diameter fitting saidconstant diameter portion of said die with a predetermined clearance,said punch member being adapted to be inserted inside said sheathwhereby a substantial portion of said desired length of said sheath issupported by said punch member, the shell thickness of said punch memberbeing constant and being of a small gauge to facilitate slipping of thesheath over the outer surface of the punch member; and means for holdingsaid punch member and said die in concentrically aligned relationshipand allowing relative linear movement between said punch and said die;said relative movement bringing a cutting edge provided by the outerperipheral edge of the free end of said punch member into proximity ofanother cutting edge provided between said constant diameter portion andthe surface of said die adjacent the stripping end of the opening insaid die with said sheath interposed therebetween and then the endportion of said punch member within said constant diameter portionwhereby said sheath is sheared along a line defined by said cuttingedges of said die and punch brought into proximity.
 2. The device ofclaim 1 further comprising: a shaft axially slidably inserted within theopening in said punch and having a first end for abutting the free endof a cable inserted into said punch member; and means coupled to theopposite end of said shaft for adjustably positioning said shaft withinsaid punch member; said punch member being adjusted to be positionedbeneath the exposed concentric layer to be removed wherein theunderlying concentric layer extends into the opening of said punch andabuts the end of said adjustable shaft to thereby control the length ofthe exposed concentric layer positioned about said punch member.